1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method for providing services by dynamically changing an operation mode of a base station in a wireless communication system.
2. Related Art
In an institute of electrical and electronics engineers (IEEE) 802.16 task group that chooses the next-generation wireless interface standards and a nonprofit worldwide interoperability for microwave access (WiMAX) forum that provides service and network standards for a broadband wireless connection system based on IEEE 802.16, standardization has been being achieved for a wireless connection system supporting a femto cell to enhance efficiency of the system and improve quality of service (QoS) under an indoor environment. The WiMAX forum defines a femto base station (BS) as a low-power inexpensive base station connected to an Internet protocol (IP) network through a fixed wireless link or a local broadband wired link.
The femto BS is connected to the IP network spread in a home or an office, and accesses a core network of a mobile communication system through the IP network, thereby providing mobile communication service. That is, the femto BS may be connected to the core network of the mobile communication system through a digital subscriber line (DSL). A user of the mobile communication system may receive the service in the outdoors through the existing macro cell, but receive the service in the indoors through the femto cell. The femto cell improves indoor coverage of the mobile communication system by making up for that the service of the existing macro cell becomes deteriorated in a building, and provides the service intended for the a specific user, thereby providing voice and data service of high quality. Further, the femto cell can provide a new service not given in the macro cell, and the spread of the femto cell may cause fixed-mobile convergence (FMC) to be accelerated and an industrial-based cost to be reduced.
The femto cell includes a closed subscriber group (CSG) cell that provides services to only a set specific user group, and a non-CSG cell that provides services general users. Here, the specific user group that can receive services from the CSG cell will be called a CSG, and a user who belongs to the corresponding group will be called a CSG user. Further, users other than the CSG users will be called a non-CSG user.
In a wireless communication system supporting the femto cell, there may exist a plurality of femto cells such as the CSG cell, the non-CSG cell, etc. in addition to the macro cell. Thus, interference may occur when a wireless signal is transmitted and received between a base station (BS) and user equipment (UE) of each cell, thereby deteriorating quality of communication. However, this conflicts with the original object of the wireless communication system supporting the femto cell to provide higher quality of services to a user.
Accordingly, there is needed a method for preventing interference between the cells in the wireless communication system supporting the femto cell to provide higher quality of services, and providing services by properly adjusting a service mode in accordance with conditions of the wireless communication system.